1. Field of the Invention
This invention relates to a wood planing machine, more particularly to a wood planing machine having a carriage locking unit for positioning a cutter carriage on the wood planing machine.
2. Description of the Related Art
FIGS. 1 to 3 illustrate a conventional wood planing machine 10 that is disclosed in U.S. Pat. No. 5,771,949. The wood planing machine 10 includes a base 11 with two pairs of upstanding posts 12 disposed at the corners of the base 11 for supporting a cutter carriage 13 thereon, a height adjusting unit (not shown) for adjusting height of the cutter carriage 13 relative to the base 11 via a handle 16 which is mounted on a top end of the wood planing machine 10, and a carriage locking mechanism 20 for positioning the cutter carriage 13 on the posts 12. The cutter carriage 13 confines with the base 11 a wood passageway therebetween for passage of a workpiece 17. The carriage locking mechanism 20 includes a locking handle 21, two pairs of cooperating first and second locking linkages 221, 222 (only one pair is shown) pivoted on the locking handle 21 and associated with the pairs of the posts 12, and a plurality of post clamps 23 respectively associated with the posts 12. The post clamps 23 are resiliently deflectable, and engage their associated posts 12 to prevent vertical translation of the cutter carriage 13. The second locking linkage 222 includes first and second members (not shown), which are telescopically related. A coiled spring 223 is disposed in the second locking linkage 222, and is captured by the first and second members. The first and second locking linkages 221, 222 are turnable relative to each other via operation of the locking handle 21 between a clamped position, in which the first and second locking linkages 221, 222 are aligned (see FIG. 3), and the coiled spring 223 urges the post clamps 23 via the first and second locking linkages 221, 222 to provide clamping forces onto the posts 12, and a release position, in which the first and second locking linkages 221, 222 form an angle (see FIG. 2), and clamping surfaces of the post clamps 23 are in loose contact with the posts 12, thereby permitting vertical translation of the cutter carriage 13.
The wood planing machine 10 is disadvantageous in that it is relatively complex to assemble the carriage locking mechanism 20. Moreover, there is a tendency for the coiled spring 223 to experience elastic fatigue after being in use for a period of time, and can cause undesirable problems, such as loosening and vibration of the cutter carriage 13 during operation of the wood planing machine 10.